WO2009145315A1

WO2009145315A1 - Radio communication device and radio communication method

Info

Publication number: WO2009145315A1
Application number: PCT/JP2009/059893
Authority: WO
Inventors: 英寛江口
Original assignee: 京セラ株式会社
Priority date: 2008-05-29
Filing date: 2009-05-29
Publication date: 2009-12-03
Also published as: KR20110009195A; US20110076938A1

Abstract

A radio communication device (100) includes: a communication quality acquisition unit (150a) which acquires communication quality of a radio propagation path to a communication partner; a retransmission quantity control unit (150b) which controls the number of retransmissions with a preset first frequency in accordance with communication quality obtained by the communication quality acquisition unit (150a); and a retransmission control unit (150c) which controls a retransmission exceeding the retransmission quantity controlled by the retransmission quantity control unit (150b) to be performed with a second frequency set for communication with the communication partner.

Description

Wireless communication apparatus and wireless communication method

Cross-reference of related applications

This application claims the priority of Japanese Patent Application No. 2008-140854 filed on May 29, 2008 and Japanese Patent Application No. 2008-140747 filed on May 29, 2008. And the entire disclosures of these earlier applications are incorporated herein by reference.

The present invention relates to a wireless communication apparatus and a wireless communication method for performing retransmission using a preset frequency when retransmitting data to a communication partner.

As a communication method for dynamically allocating time / frequency resources, there is, for example, “LTE (Long Term Evolution”) positioned as 3.9 G in 3GPP (3rd Generation Partnership Project). In such a communication method that dynamically allocates time / frequency resources, in order to reduce overhead when performing packet communication (for example, VoIP (Voice Over Internet Protocol)) in which a certain amount of stable communication amount is maintained, A method of allocating radio resources in a fixed manner is being studied.

FIG. 11 is a diagram for explaining a fixed scheduling example (conventional example 1) in which resources for retransmission are fixedly allocated to a predetermined frequency channel every two unit times. In the figure, resources with diagonal lines extending from upper right to lower left are fixedly allocated resources. In this fixed scheduling example, after the initial transmission of data to the communication partner, a resource for retransmission is secured for a total of four times every two unit times in the same frequency channel. One data transmission period is set. In the first transmission period, data was retransmitted twice with fixed allocation to the communication partner after the first transmission, so that there are 2 empty resources (resources with diagonal lines from the upper left to the lower right in the figure) without retransmission. Has occurred batch. In addition, in the next transmission period, data was retransmitted once by fixed assignment to the communication partner after the first transmission, so there is no retransmission (empty resource with a diagonal line from the upper left to the lower right in the figure) Has occurred three times.

In order to avoid the occurrence of such unused unused resources, as shown in FIG. 12, an “initial fixed / retransmission dynamic scheduling example (conventional example 2)” has been proposed. In this figure, only the first transmission corresponding to the resource with the diagonal line from the upper right to the lower left in the figure is fixedly allocated, and the resource is dynamically allocated at the time of retransmission corresponding to the resource with the meshed diagonal line in the figure. To be assigned.

In the case of the fixed scheduling of Conventional Example 1, empty resources are generated as shown in FIG. 11 in an environment where the communication quality is good. Therefore, the resources are effective unless resources are dynamically reassigned to other users. The problem arises that it cannot be used. An environment with good communication quality includes, for example, a case where the communication partner is not moving or a case where the moving speed of the communication partner is extremely low.

Further, in the case of the first fixed / retransmission dynamic scheduling of the conventional example 2, in an environment where the radio environment is deteriorated, retransmission (that is, dynamic allocation) occurs frequently, resulting in a problem that overhead is increased. Examples of the environment in which the wireless environment has deteriorated include a case where the moving speed of the communication partner is high and fading increases.

The present invention relates to a technique (a wireless communication apparatus and a wireless communication method) that improves both frequency utilization efficiency by optimizing both empty resources at the time of retransmission and overhead due to dynamic allocation in a communication scheme that performs fixed allocation at a preset frequency. ).

A wireless communication apparatus according to a first aspect of the present invention that achieves the above object is
When retransmitting data to a communication partner, a wireless communication device that performs the retransmission using a preset frequency,
A communication quality acquisition unit for acquiring communication quality of a radio propagation path between the communication partners;
In accordance with the communication quality acquired by the communication quality acquisition unit, a retransmission number control unit that controls the number of retransmissions at a preset first frequency;
A retransmission control unit that controls to perform retransmission at a second frequency set with the communication partner for retransmission exceeding the number of retransmissions controlled by the retransmission number control unit. To do.

The invention according to a second aspect is the wireless communication device according to the first aspect,
The retransmission number control unit controls the number of retransmissions to decrease as the communication quality acquired by the communication quality acquisition unit increases.

The invention according to a third aspect is the wireless communication device according to the first or second aspect,
The retransmission number control unit controls the number of retransmissions so that retransmission at the first frequency is stopped when the communication quality acquired by the communication quality acquisition unit exceeds a predetermined communication quality. It is what.

A wireless communication method according to a fourth aspect of the present invention that achieves the above object is
When retransmitting data to a communication partner, a wireless communication method for performing the retransmission using a preset frequency,
A communication quality acquisition step of acquiring communication quality of a radio propagation path between the communication partners;
A retransmission count control step for controlling the number of retransmissions at a preset first frequency according to the communication quality acquired in the communication quality acquisition step;
For retransmission exceeding the number of retransmissions controlled in the retransmission number control step, a retransmission control step for controlling to perform the retransmission at a second frequency set with the communication partner;
It is characterized by performing.

Furthermore, a wireless communication apparatus according to a fifth aspect of the present invention that achieves the above object is
When retransmitting data to a communication partner, a wireless communication apparatus that performs the retransmission using a preset frequency,
A moving speed acquisition unit that acquires the moving speed of the communication partner;
A retransmission number control unit that controls the number of retransmissions at a preset first frequency according to the moving speed of the communication partner acquired by the moving speed acquisition unit;
For retransmission exceeding the number of retransmissions controlled by the retransmission number control unit, a retransmission control unit that controls to perform the retransmission at a second frequency set with the communication partner;
It is characterized by providing.

An invention according to a sixth aspect is the wireless communication apparatus according to the fifth aspect,
The retransmission number control unit controls the number of retransmissions to decrease as the movement speed of the communication partner acquired by the movement speed acquisition unit decreases.

The invention according to a seventh aspect is the wireless communication apparatus according to the fifth or sixth aspect,
The retransmission number control unit controls the number of retransmissions so that retransmission at the first frequency is stopped when the movement speed of the communication partner acquired by the movement speed acquisition unit is less than a predetermined speed. It is characterized by this.

The invention according to an eighth aspect is the wireless communication apparatus according to any one of the fifth to seventh aspects,
The moving speed acquisition unit acquires the moving speed of the communication partner by being notified of the moving speed of the communication partner measured by the communication partner.

A wireless communication method according to a ninth aspect of the present invention that achieves the above object is
When retransmitting data to a communication partner, a wireless communication method for performing the retransmission using a preset frequency,
A moving speed acquisition step of acquiring the moving speed of the communication partner;
A retransmission number control step for controlling the number of retransmissions at a preset first frequency according to the movement speed of the communication partner acquired in the movement speed acquisition step;
For retransmission exceeding the number of retransmissions controlled in the retransmission number control step, a retransmission control step for controlling to perform the retransmission at the second frequency set with the communication partner;
It is characterized by performing.

It is a block diagram which shows schematic structure of the radio | wireless communication apparatus (base station) which concerns on 1st Embodiment of this invention. It is a flowchart which illustrates the allocation method determination procedure in the radio | wireless communication method which the radio | wireless communication apparatus (base station) which concerns on 1st Embodiment performs. It is a figure which shows the operation example of the allocation system determination procedure of FIG. It is a flowchart which illustrates the allocation system change procedure in the radio | wireless communication method which the radio | wireless communication apparatus (base station) which concerns on 1st Embodiment performs. It is a block diagram which shows schematic structure of the radio | wireless communication apparatus (base station) which concerns on 2nd Embodiment of this invention. It is a flowchart which illustrates the procedure which acquires in the communicating party (terminal) the moving speed used with the radio | wireless communication method which the radio | wireless communication apparatus (base station) which concerns on 2nd Embodiment performs. In the wireless communication method executed by the wireless communication apparatus (base station) according to the second embodiment, the wireless communication apparatus (base station) acquires the moving speed of the terminal from the communication partner (terminal) and communicates the number of retransmissions, etc. It is a figure which illustrates the allocation system determination sequence instruct | indicated to the other party (terminal). It is a flowchart which illustrates the allocation method determination procedure in the radio | wireless communication method which the radio | wireless communication apparatus (base station) which concerns on 2nd Embodiment performs. It is a figure which shows the operation example of the allocation method determination procedure of FIG. It is a flowchart which illustrates the allocation system change procedure in the radio | wireless communication method which the radio | wireless communication apparatus (base station) which concerns on 2nd Embodiment performs. It is a figure for demonstrating the fixed scheduling example (conventional example 1) which carries out fixed allocation of the resource for resending to a predetermined frequency channel. It is a figure for demonstrating the example of an initial fixed and resending dynamic scheduling (conventional example 2) which carries out fixed allocation of the resource for resending to the predetermined frequency channel only for the first time, and dynamically allocating the resource for resending after that.

Hereinafter, each embodiment for carrying out the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a wireless communication apparatus according to the first embodiment of the present invention. The wireless communication apparatus (base station) 100 according to the first embodiment is configured to be able to perform data communication corresponding to a predetermined communication method (for example, LTE). As shown in FIG. 1, a radio communication apparatus (base station) 100 includes an antenna 110, an RF unit 130, an RF control unit 140, a system control unit 150, an input unit 160, a display unit 170, and a system memory. Part 180 and the like. The RF control unit 140 includes a reception unit 140a and a transmission unit 140b. The system control unit 150 includes a communication quality acquisition unit 150a, a retransmission number control unit 150b, and a retransmission control unit 150c. The system storage unit 180 includes a communication quality information storage unit 180a.

The RF unit 130 converts data to be transmitted by a predetermined communication method into a high-frequency signal and transmits it from the antenna 110, and converts the high-frequency signal input from the antenna 110 into a data signal. The RF control unit 140 controls communication (transmission / reception) of a predetermined communication method, and measures the strength of an electric field (RSSI or the like) from a wireless communication device (terminal) that is a communication partner received by an antenna. The RF control unit 140 functions as a reception unit 140 a and a transmission unit 140 b corresponding to the data signal input from the RF unit 130 and the data signal output to the RF unit 130.

The system control unit 150 is a control unit that controls each unit of the base station 100 in an integrated manner.

The communication quality acquisition unit 150a acquires the communication quality of the wireless propagation path with the communication partner (terminal). The communication quality acquired by the communication quality acquisition unit 150a is stored in the communication quality information storage unit 180a of the system storage unit 180 as communication quality information such as uplink or downlink SINR, CINR, and Doppler frequency. In this case, when using uplink information, the wireless communication device (base station) 100 measures the transmission signal of the communication partner (terminal), and acquires the information. When downlink information is used, the wireless communication apparatus (base station) 100 receives the feedback signal from the communication partner (terminal) to acquire the information.

The communication quality can be expressed in stages, for example, communication quality level 1, communication quality level 2, communication quality level 3,. Here, the communication quality level 1 is the highest communication quality, the communication quality level 2 is the next highest communication quality, and the communication quality level 3,...

Table 1 shows an example of the definition of the communication quality level. In the example of Table 1, a case where 50% or more transmission succeeds with 0 retransmissions (no retransmission) is defined as communication quality level 1. When transmission of 50% or more succeeds after one retransmission, it is defined as communication quality level 2, and when transmission of 50% or more succeeds after two retransmissions, it is defined as communication quality level 3. Thereafter, communication quality level 4 and later are defined in the same manner as described above as necessary.

In addition, the definition of the communication quality level shown in Table 1 is not limited to this, and can be changed to various modes as necessary. For example, when “reduction of overhead when performing dynamic allocation” is more important than “reduction of empty resources when retransmission does not occur”, “50%” in the definition of the communication quality level is “ Set to a “predetermined value less than 50%”. Further, when “reduction of empty resources when no retransmission occurs” is more important than “reduction of overhead when performing dynamic allocation”, “50%” in the definition of the communication quality level is set to “50%”. Set to a “predetermined value exceeding 50%”.

The retransmission number control unit 150b controls the number of retransmissions at a preset first frequency according to the communication quality acquired by the communication quality acquisition unit 150a. Specifically, the fixed number of retransmissions is set based on the relationship between the communication quality level and the number of retransmissions shown in Table 1. At that time, as shown in Table 1, the retransmission number control unit 150b increases the number of retransmissions as the communication quality (communication quality level) acquired by the communication quality acquisition unit 150a decreases, and is acquired by the communication quality acquisition unit 150a. Control is performed so that the number of retransmissions decreases as the communication quality (communication quality level) increases. At the same time, when the communication quality (communication quality level) acquired by the communication quality acquisition unit 150a exceeds a predetermined communication quality (for example, when communication quality level 1 is the highest communication quality) ), The number of retransmissions is controlled to be 0 so that retransmission at the first frequency is stopped.

The retransmission control unit 150c performs retransmission at the first frequency for the number of retransmissions controlled by the retransmission number control unit 150b, and for a retransmission exceeding the number of retransmissions controlled by the retransmission number control unit 150b, the communication partner (terminal ) To perform the retransmission at a second frequency arbitrarily set between In this case, the second frequency may be different from the first frequency or may be the same frequency as the first frequency in some cases. In addition, when the retransmission control unit 150c is controlled by the retransmission number control unit 150b to set the number of retransmissions to 0 so that retransmission at the first frequency stops, the retransmission control unit 150c uses the second frequency. Perform all retransmissions (perform all retransmissions with dynamic allocation).

The input unit 160 is used when inputting information or selecting one of the options displayed on the display screen of the display unit 170, and has various keys and various buttons. Note that the input unit 160 and the display unit 170 may be omitted as necessary.

The system storage unit 180 is configured by a memory such as a RAM, and stores application programs and temporary data. The communication quality information storage unit 180a stores the communication quality acquired by the communication quality acquisition unit 150a as communication quality information such as uplink SINR, downlink SINR, CINR, and Doppler frequency.

[Flow chart of allocation method determination procedure]
FIG. 2 is a flowchart illustrating an allocation method determination procedure in the radio communication method executed by radio communication apparatus (base station) 100 according to the first embodiment. The allocation method determination procedure in FIG. 2 is started at the start of communication (at the start of wireless access).

First, in step S11, the communication quality acquisition unit 150a acquires the communication quality (communication quality level) of the wireless propagation path with the communication partner (terminal). In the next step S12, the retransmission number control unit 150b determines whether or not the first transmission of data to the communication partner (terminal) is fixed allocation. If the first transmission is not fixed allocation in step S12, the process proceeds to step S13, and the retransmission number control unit 150b dynamically allocates all transmissions including the first transmission and retransmission. On the other hand, if the first transmission is fixed assignment in step S12, the process proceeds to step S14. In step S12, whether or not the initial transmission of data to the communication partner (terminal) is fixed allocation is determined based on, for example, QoS (QualityＱof Service).

In step S14, the retransmission number control unit 150b fixedly assigns the number of retransmissions at the first frequency set in advance according to the communication quality acquired by the communication quality acquisition unit 150a in step S11, and sets the number of retransmissions. Dynamically assign more retransmissions to the second frequency. That is, in step S14, the retransmission number control unit 150b first determines whether the communication quality level acquired in step S11 is the communication quality level 1, the communication quality level 2, the communication quality level 3,. Then, according to the determination result, if the communication quality level is level 1, the process proceeds to step S15, if it is level 2, the process proceeds to step S16, and if it is level 3, the process proceeds to step S17. Perform step processing.

In step S15 that proceeds to the communication quality level 1 that is the highest communication quality, since the communication quality is very good, the probability of retransmission occurring is reduced, the occurrence of empty resources is reduced, and all retransmissions are performed. Dynamic allocation can perform efficient communication. In consideration of this, the retransmission number control unit 150b controls the number of retransmissions to 0 so that retransmission (fixed allocation) at a preset first frequency is stopped, and all retransmissions are second. Dynamic allocation to the frequency of In step S16 that proceeds to the case of communication quality level 2 that is the second highest communication quality, retransmission number control section 150b controls the number of retransmissions for fixed allocation to 1, performs fixed allocation for one retransmission, and performs the second retransmission. Dynamically allocate the rest. In step S17 that proceeds to the case of communication quality level 3, which is an environment in which communication quality has deteriorated, retransmissions occur more frequently, and the fixed assignment up to a certain number of retransmissions reduces the overhead when performing dynamic assignment. In consideration of this, the retransmission count control unit 150b controls the fixed allocation retransmission count to 2, performs fixed allocation of 2 retransmissions, and dynamically allocates the 3rd and subsequent retransmissions.

FIG. 3 is a diagram illustrating an operation example of the allocation method determination procedure described in FIG. FIG. 3 shows an “operation example in a scheduling example in which fixed retransmission is performed up to two retransmissions and dynamic retransmission is then allocated”. In FIG. 3, in the first transmission period corresponding to step S17 of FIG. 2, after the first transmission, data retransmission by fixed allocation to the communication partner is performed twice, and then data retransmission by dynamic allocation is performed once. It has been broken. For this reason, there is no empty resource without retransmission, and data is retransmitted once by dynamic allocation. Therefore, the overhead for performing dynamic allocation is two times in the conventional example 2 shown in FIG. 12, but is reduced to one time in FIG. In FIG. 3, in the next transmission period corresponding to step S17 in FIG. 2, data is retransmitted only once by fixed assignment to the communication partner after the first transmission. For this reason, in FIG. 3, there is one empty resource that does not have retransmission, but the empty resource is significantly reduced as compared to three in the conventional example 1 shown in FIG. 11.

In the wireless communication apparatus (base station) and the wireless communication method executed by the wireless communication apparatus (base station) according to the first embodiment, the allocation method determination procedure of FIG. 2 is performed. That is, at the start of communication, according to the communication quality level, the number of retransmissions is controlled so that the number of retransmissions increases as the communication quality level is low, and the number of retransmissions decreases as the communication quality level is high. Retransmission is performed using the first frequency set in advance for the number of retransmissions. On the other hand, for retransmission exceeding the number of retransmissions, the number of retransmissions is controlled so that the number of retransmissions of dynamic allocation increases as the communication quality level becomes better, and is arbitrarily set with the communication partner (terminal) by the number of retransmissions Control is performed so that retransmission is performed at the second frequency. As described above, in the first embodiment, as the communication quality deteriorates, the number of times of fixed allocation of retransmissions is increased according to the degree of communication quality, and as the communication quality becomes better, the number of times of fixed allocation of retransmissions is decreased. Increase the number of times to dynamically allocate retransmissions. As a result, it is possible to reduce both empty resources during retransmission and overhead due to dynamic allocation, and it is possible to optimize both empty resources during retransmission and overhead due to dynamic allocation to improve frequency utilization efficiency.

[Flow chart of allocation method change procedure]
The timing for determining the allocation method in the allocation method determination procedure of FIG. 2 is at the start of communication. However, it is desirable that the allocation method determined at the start of communication can be changed during communication (when a transmission packet is generated) in accordance with the subsequent change in communication quality.

FIG. 4 is a flowchart illustrating an allocation method change procedure in the wireless communication method executed by the wireless communication apparatus (base station) 100 according to the first embodiment. The allocation method change procedure shown in FIG. 4 is to change the allocation method determined by the allocation method determination procedure of FIG. 2 according to the change in communication quality, and is executed at regular intervals.

In the allocation method changing procedure, first, in step S21, the communication quality acquisition unit 150a acquires the communication quality (communication quality level) of the wireless propagation path with the communication partner (terminal). In the next step S22, the retransmission number control unit 150b determines whether or not the first transmission of data to the communication partner (terminal) is fixed allocation. In step S22, when the first transmission is not fixed allocation, the process proceeds to step S23, and retransmission number control section 150b dynamically allocates all transmissions including the first transmission and retransmission. On the other hand, if the first transmission is fixed assignment in step S22, the process proceeds to step S24. In step S12, whether or not the initial transmission of data to the communication partner (terminal) is fixed allocation is determined based on, for example, QoS (QualityＱof Service).

In step S24, the retransmission number control unit 150b assigns a fixed number of retransmissions at a preset first frequency according to the communication quality acquired by the communication quality acquisition unit 150a in step S21, and sets the number of retransmissions. Dynamically assign more retransmissions to the second frequency. That is, in step S24, the retransmission number control unit 150b first determines whether the communication quality level acquired in step S21 is the communication quality level 1, the communication quality level 2, the communication quality level 3,. Then, according to the determination result, if the communication quality level is level 1, the process proceeds to step S25, if it is level 2, the process proceeds to step S26, and if it is level 3, the process proceeds to step S27. Perform step processing.

In step S25 that proceeds to communication quality level 1, which is the highest communication quality, since the communication quality is extremely good, the probability of occurrence of retransmission is reduced, the occurrence of empty resources is reduced, and all retransmissions are performed. Dynamic allocation can perform efficient communication. In consideration of this, the retransmission number control unit 150b controls the number of retransmissions to 0 so that retransmission (fixed allocation) at a preset first frequency is stopped, and all retransmissions are second. Dynamic allocation to the frequency of In step S26 that proceeds to the case of communication quality level 2 that is the second highest communication quality, retransmission number control section 150b controls the number of retransmissions of fixed assignment to 1, assigns a single retransmission, and assigns a second retransmission. Dynamically allocate the rest. In step S27, which proceeds in the case of communication quality level 3, which is an environment in which communication quality has deteriorated, retransmissions occur more frequently, and the fixed allocation up to a certain number of retransmissions reduces the overhead when performing dynamic allocation. In consideration of this, the retransmission count control unit 150b controls the fixed allocation retransmission count to 2, performs fixed allocation of 2 retransmissions, and dynamically allocates the 3rd and subsequent retransmissions.

In the next step S28, the retransmission number control unit 150b determines whether or not the allocation scheme determined in step S25, step S26 or step S27 matches the current allocation scheme. In step S28, when the current allocation method matches the allocation method determined in the preceding step (step S25, step S26 or step S27), the process proceeds to step S29 and the current allocation method is maintained. On the other hand, if the current allocation method and the allocation method determined in the preceding step do not match in step S28, the process proceeds to step S30, and the retransmission number control unit 150b sets the allocation method to steps S25 and S26. Alternatively, the allocation method determined in step S27 is changed. In addition, after execution of step S29 or step S30, it returns to step S21 and repeats the said allocation system change procedure. For this reason, when a transmission packet is generated, the allocation method is changed at any time according to a change in communication quality.

In the wireless communication apparatus (base station) and the wireless communication method executed by the wireless communication apparatus (base station) according to the first embodiment, the allocation method determination procedure of FIG. 4 is performed. In other words, not only at the start of communication but also during communication, depending on the communication quality level, the number of retransmissions increases as the communication quality level decreases, and the number of retransmissions decreases as the communication quality level increases. The number of times is controlled, and retransmission is performed using the preset first frequency for the number of times of retransmission. On the other hand, for retransmission exceeding the number of retransmissions, the number of retransmissions is controlled so that the number of retransmissions of dynamic allocation increases as the communication quality level becomes better, and is arbitrarily set with the communication partner (terminal) by the number of retransmissions Control is performed so that retransmission is performed at the second frequency. As described above, in the first embodiment, as the communication quality deteriorates, the number of times of fixed allocation of retransmissions is increased according to the degree of communication quality, and as the communication quality becomes better, the number of times of fixed allocation of retransmissions is decreased. Increase the number of times to dynamically allocate retransmissions. As a result, it is possible to reduce both empty resources during retransmission and overhead due to dynamic allocation, and it is possible to optimize both empty resources during retransmission and overhead due to dynamic allocation to improve frequency utilization efficiency.

The outline of the allocation method determination procedure and the allocation method change procedure in the wireless communication apparatus (base station) of the first embodiment described above is as follows. That is, according to the communication quality level, the number of retransmissions is increased as the communication quality level is lower, and the number of retransmissions is fixed so that the number of retransmissions is decreased as the communication quality level is higher. Assign. However, for example, the following allocation scheme determination procedure and allocation scheme change procedure can be used in combination. That is, according to the movement speed of the communication partner (terminal), the number of retransmissions increases as the movement speed increases, and the number of retransmissions is fixed so that the number of retransmissions decreases as the movement speed decreases. Is dynamically allocated. The case where the latter assignment method determination procedure and assignment method change procedure that can be used together in this way are used alone will be further described below.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 5 is a block diagram showing a schematic configuration of a wireless communication apparatus according to the second embodiment of the present invention. Radio communication apparatus (base station) 300 according to the second embodiment is configured to perform data communication corresponding to a predetermined communication method (for example, LTE). Radio communication apparatus (base station) 300 according to the second embodiment changes the internal configuration of system control unit 150 and system storage unit 180 in radio communication apparatus (base station) 100 according to the first embodiment described above. It is a thing. Accordingly, the same functional blocks as those of radio communication apparatus (base station) 100 according to the first embodiment shown in FIG.

As shown in FIG. 5, a radio communication apparatus (base station) 300 includes an antenna 110, an RF unit 130, an RF control unit 140, a system control unit 150, an input unit 160, a display unit 170, and a system storage. Part 180 and the like. The RF control unit 140 includes a reception unit 140a and a transmission unit 140b. In radio communication apparatus (base station) 300 according to the second embodiment, system control unit 150 includes moving speed acquisition unit 350a, retransmission number control unit 150b, and retransmission control unit 150c. In addition, the system storage unit 180 includes a moving speed information storage unit 380a.

The system control unit 150 is a control unit that controls each unit of the base station 300 in an integrated manner.

The moving speed acquisition unit 350a acquires the moving speed of the communication partner (terminal). The movement speed acquired by the movement speed acquisition unit 350a is stored in the movement speed information storage unit 380a of the system storage unit 180 as movement speed information. At that time, the moving speed acquisition unit 350a is notified of the moving speed of the communication partner (terminal) measured by the communication partner (terminal) according to the sequence of FIG. To get.

The moving speed of the communication partner (terminal) is, for example, an ultra-low speed area (less than 1 km / h), a low speed area (1 to 5 km / h), a medium speed area (5 to 80 km / h), and a high speed area (80 km / h or more). ),... The moving speed acquisition unit 350a determines which moving speed corresponds to one of the divided speed areas. In this way, the retransmission speed control unit 150b classifies the movement speed determined by the movement speed acquisition unit 350a into any one of “ultra low speed”, “low speed”, “medium speed”, “high speed”,. To do. Here, “Ultra-low speed” is the moving speed at which the highest communication quality can be expected, “Low speed” is the moving speed at which the next highest communication quality can be expected, and “Medium speed”, “High speed”, and so on. As the communication quality decreases.

Table 2 shows an example of the definition of the speed area of the above moving speed. In the example of Table 2, a case where transmission of 50% or more succeeds when the number of retransmissions is 0 (no retransmission) is defined as “very low speed”. If transmission of 50% or more succeeds after one retransmission, define it as “low speed”. If transmission of 50% or more succeeds in two retransmissions, define it as “medium speed” and send more than 50%. Is defined as “high-speed” when it succeeds after 3 retransmissions. From this point onward, “ultra-high speed” or the like is defined in the same manner as described above, if necessary.

In addition, the definition of the speed region of the moving speed shown in Table 2 is not limited to this, and can be changed to various modes as necessary. For example, in the case where “reduction of overhead when performing dynamic allocation” is more important than “reduction of empty resources when retransmission does not occur”, “50%” in the definition of the speed region of the moving speed is used. Is set to “a predetermined value less than 50%”. In addition, when “reducing empty resources when no retransmission occurs” is more important than “reducing overhead when performing dynamic allocation”, “50%” in the definition of the speed region of the moving speed is used. Is set to a “predetermined value exceeding 50%”. In addition, the upper limit value and the lower limit value of each speed region of the moving speed shown in Table 2 differ in “relationship between moving speed and communication quality” for each communication method applied to the wireless communication apparatus according to the second embodiment. In view of this, it may be set as appropriate so as to be an optimum value in the communication system to be applied.

The retransmission number control unit 150b controls the number of retransmissions at a preset first frequency according to the movement speed of the communication partner (terminal) acquired by the movement speed acquisition unit 350a. Specifically, the number of retransmissions to be fixedly assigned is set based on the relationship between the movement speed of the communication partner (terminal) and the number of retransmissions shown in Table 2. At that time, as shown in Table 2, the retransmission number control unit 150b increases the number of retransmissions as the movement speed of the communication partner (terminal) acquired by the movement speed acquisition unit 350a increases, and the movement speed acquisition unit 350a Control is performed so that the number of retransmissions decreases as the movement speed of the acquired communication partner (terminal) decreases. At the same time, when the movement speed of the communication partner (terminal) acquired by the movement speed acquisition section 350a is less than a predetermined speed (in the case of Table 2, less than 1 km / h), the number-of-retransmissions control section 150b Control is performed so that the number of retransmissions is zero so that retransmissions at a certain frequency are stopped.

The system storage unit 180 is configured by a memory such as a RAM, and stores application programs and temporary data. The moving speed information storage unit 380a sets the moving speed of the communication partner (terminal) acquired by the moving speed acquisition unit 350a to any one of “ultra low speed”, “low speed”, “medium speed”, “high speed”,. Or stored as one piece of moving speed information.

Next, communication partner (terminal) 200 that communicates with radio communication apparatus (base station) 300 according to the second embodiment will be described. The wireless communication apparatus (base station) 300 according to the second embodiment has a “moving speed acquisition unit having a function of periodically acquiring (detecting) the moving speed of the terminal” as the communication partner (terminal) 200. It communicates with the wireless communication terminal provided. Specifically, the communication partner (terminal) 200 is a wireless device configured to periodically acquire (detect) the moving speed of the terminal using one of the two types of moving speed detection methods described below. A communication terminal.

[Movement speed detection method 1: Method of using position information acquired by GPS]
Using the position information acquired by GPS, the moving distance is calculated from the position information at the previous monitoring time and the position information at the current monitoring time, and the moving speed is detected (calculated) from the time difference between the previous time and the current time. For example, in the Northern Hemisphere, the previous monitoring time is t0 (h), the current monitoring time is t1 (h), the longitude / latitude at t0 is x0 · y0, and the longitude / latitude at t1 is x1 · h. Let y1. The moving distance r (km) and moving speed v (km / h) at this time are obtained by the following equations (1) and (2), respectively.

[Moving speed detection method 2: Method using Doppler shift of frequency of base station or peripheral base station of communication partner]
In general, a mobile that moves at a speed v toward a base station in a stationary state observes a frequency f ′ represented by the following equation (3) with respect to a radio frequency f transmitted from the base station.

Here, c is the speed of light (the speed of radio waves). From the above equation (3), the velocity v of the moving body is obtained by the following equation (4).

The speed v of the moving body is a speed when the moving body is moving toward the base station direction. Therefore, when the moving body moves in a direction deviating from the base station direction by an average angle θ, The relationship (5) is established.

Here, when only observing the frequency of the communication partner base station, since the value of θ cannot be determined, it is assumed that θ = π / 4, which is the median of 0 ≦ θ ≦ π / 2, The moving speed v is calculated by the following equation (6).

[Flowchart for obtaining movement speed of communication partner (terminal)]
FIG. 6 is a flowchart illustrating a procedure in which the communication partner (terminal) 200 acquires the moving speed used in the wireless communication method executed by the wireless communication apparatus (base station) 300 according to the second embodiment. The moving speed acquisition procedure of FIG. 6 is started at the start of moving speed monitoring.

First, in step S01, the communication partner (terminal) 200 acquires the moving speed of the terminal by the moving speed detection method 1 or the moving speed detection method 2. As for the movement speed acquired in step S41, if the terminal is within the range, the loop of step S41 is repeated again through step S42, step S43, and step S44. Thus, if the terminal is within range, the acquired moving speed is updated every predetermined period (every 10 seconds) determined by the timer value (for example, 10 seconds) of the moving speed monitoring timer. Note that when the terminal is out of service, communication is interrupted, and thus the acquisition (monitoring) of the moving speed is terminated.

[Example of allocation method determination sequence]
FIG. 7 shows a wireless communication method executed by the wireless communication apparatus (base station) according to the second embodiment, where the wireless communication apparatus (base station) acquires the moving speed of the terminal from the communication partner (terminal), It is a figure which illustrates the allocation system determination sequence which instruct | indicates the frequency | count of resending etc. to the communicating party (terminal).

As shown in FIG. 7, while the communication partner (terminal) 200 periodically acquires (detects) the moving speed of the terminal, the communication partner (terminal) 200 and the wireless communication device (base station) 300 Suppose that wireless access is started. As described above, when wireless access is started between the communication partner (terminal) 200 and the wireless communication device (base station) 300, the communication partner (terminal) 200 determines the obtained movement speed of the terminal as the wireless communication device. (Base station) 300 is notified. The wireless communication apparatus (base station) 300 that has received the notification of the moving speed of the terminal determines the number of retransmissions at the first frequency set in advance, the allocation method (fixed allocation, dynamic allocation), etc. ) 200 is instructed.

[Flow chart of allocation method determination procedure]
FIG. 8 is a flowchart illustrating an allocation method determination procedure in the wireless communication method executed by wireless communication apparatus (base station) 300 according to the second embodiment. The allocation method determination procedure in FIG. 8 is activated at the start of communication (at the start of wireless access).

First, in step S51, the moving speed acquisition unit 350a acquires the moving speed of the communication partner (terminal). In the next step S52, the retransmission number control unit 150b determines whether or not the first transmission of data to the communication partner (terminal) is fixed allocation. In step S52, if the first transmission is not fixed allocation, the process proceeds to step S53, and retransmission number control section 150b dynamically allocates all transmissions including the first transmission and retransmission. On the other hand, if the first transmission is fixed assignment in step S52, the process proceeds to step S54. In step S52, whether or not the initial transmission of data to the communication partner (terminal) is fixed allocation is determined based on, for example, QoS (QualityＱof Service).

In step S54, the retransmission number control unit 150b assigns a fixed number of retransmissions at a preset first frequency according to the movement speed of the communication partner (terminal) acquired in step S51, and sets the number of retransmissions. Dynamically assign more retransmissions to the second frequency. That is, in step S54, the retransmission number control unit 150b first sets the movement speed of the communication partner (terminal) acquired in step S51 to “ultra low speed”, “low speed”, “medium speed”, “high speed”,. Which one is determined. Then, according to the determination result, if the moving speed is “ultra low speed”, the process proceeds to step S55, if “low speed”, the process proceeds to step S56, and if “middle speed”, the process proceeds to step S57. If so, the process proceeds to step S58, and the retransmission number control unit 150b performs the process of each step.

In step S55, which proceeds to "ultra-low speed" where the highest communication quality can be expected, the communication quality is extremely good, so the probability of retransmission occurring is reduced, the generation of empty resources is reduced, and all retransmissions are performed dynamically. The assigned one can perform efficient communication. In consideration of this, the retransmission number control unit 150b controls the number of retransmissions to 0 so that retransmission (fixed allocation) at a preset first frequency is stopped, and all retransmissions are second. Dynamic allocation to the frequency of In step S56, which proceeds in the case of “low speed” in which the second highest communication quality can be expected, the retransmission number control unit 150b controls the number of retransmissions for fixed allocation to 1, performs fixed allocation for one retransmission, and performs the second retransmission. Dynamically allocate the rest. In step S57, which proceeds in the case of “medium speed” where there is a possibility that the communication quality may be deteriorated, the retransmission number control unit 150b controls the fixed number of retransmissions to 2 and assigns the two retransmissions fixedly, Dynamic allocation is performed after the third retransmission. In step S58, which proceeds in the case of “high speed” where there is a high possibility that the communication quality is deteriorated, the retransmission number control unit 150b controls the fixed allocation retransmission number to 3, and allocates 3 retransmissions fixedly, Dynamic allocation is performed after the fourth retransmission.

FIG. 9 is a diagram illustrating an operation example of the allocation method determination procedure described in FIG. FIG. 9 shows an “operation example in a scheduling example in which fixed retransmissions up to two retransmissions are allocated and dynamic retransmissions are subsequently allocated”. In FIG. 9, in the first transmission period corresponding to step S57 in FIG. 8, after the first transmission, data retransmission by fixed allocation to the communication partner is performed twice, and then data retransmission by dynamic allocation is performed once. It has been broken. For this reason, there is no empty resource without retransmission, and data is retransmitted once by dynamic allocation. Therefore, the overhead for performing dynamic allocation is two times in the conventional example 2 shown in FIG. 12, but is reduced to one time in FIG. In FIG. 9, in the next transmission period corresponding to step S <b> 57 in FIG. 8, data is retransmitted only once by fixed allocation to the communication partner after the first transmission. For this reason, in FIG. 9, empty resources without retransmission are generated once, but the empty resources are greatly reduced as compared with the case of three times in the conventional example 1 shown in FIG.

In the wireless communication apparatus (base station) and the wireless communication method executed by the wireless communication apparatus (base station) according to the second embodiment, the allocation method determination procedure of FIG. 8 is performed. That is, at the start of communication, depending on the moving speed of the communication partner (terminal), the number of retransmissions increases as the moving speed of the communication partner (terminal) increases, and the moving speed of the communication partner (terminal) decreases. The number of retransmissions for fixed allocation is controlled so that the number of retransmissions is reduced, and retransmission is performed using the first frequency set in advance for the number of retransmissions. On the other hand, for retransmissions that exceed the number of retransmissions, the number of retransmissions is controlled so that the number of retransmissions for dynamic allocation increases as the movement speed decreases, and is arbitrarily set with the communication partner (terminal) for the number of retransmissions. Control is performed to perform retransmission at the second frequency. As described above, in the second embodiment, the number of times that retransmission is fixedly allocated is increased according to the degree of communication quality as the communication quality deteriorates as the moving speed of the communication partner (terminal) increases. At the same time, in the second embodiment, the number of times of fixed allocation of retransmissions is reduced and the number of times of dynamic allocation of retransmissions is increased as the communication quality improves as the moving speed of the communication partner (terminal) decreases. As a result, it is possible to reduce both empty resources during retransmission and overhead due to dynamic allocation, and it is possible to optimize both empty resources during retransmission and overhead due to dynamic allocation to improve frequency utilization efficiency.

[Flow chart of allocation method change procedure]
The timing for determining the allocation method in the allocation method determination procedure of FIG. 8 is when communication is started. However, it is desirable that the allocation method determined at the start of communication can be changed during communication (when a transmission packet is generated) in accordance with the subsequent change in communication quality.

FIG. 10 is a flowchart illustrating an allocation method change procedure in the radio communication method executed by radio communication apparatus (base station) 300 according to the second embodiment. The allocation method change procedure shown in FIG. 10 is to change the allocation method determined by the allocation method determination procedure of FIG. 8 according to a change in communication quality, and is executed at regular intervals.

In the allocation method changing procedure, first, in step S61, the movement speed acquisition unit 350a acquires the movement speed of the communication partner (terminal). In next step S62, the retransmission number control unit 150b determines whether or not the first transmission of data to the communication partner (terminal) is fixed allocation. If the first transmission is not fixed allocation in step S62, the process proceeds to step S63, and the retransmission number control unit 150b dynamically allocates all transmissions including the first transmission and retransmission. On the other hand, if the first transmission is fixed assignment in step S62, the process proceeds to step S64. In step S62, whether or not the initial transmission of data to the communication partner (terminal) is fixed allocation is determined based on, for example, QoS (QualityＱof Service).

In step S64, the retransmission number control unit 150b fixedly allocates the number of retransmissions at the preset first frequency according to the moving speed of the communication partner (terminal) acquired by the communication quality acquisition unit 150a in step S61. At the same time, retransmissions exceeding the number of retransmissions are dynamically allocated to the second frequency. That is, in step S64, the retransmission number control unit 150b first sets the movement speed of the communication partner (terminal) acquired in step S61 to “ultra low speed”, “low speed”, “medium speed”, “high speed”,. Which one is determined. Then, according to the determination result, if the moving speed is “ultra low speed”, the process proceeds to step S65, if “low speed”, the process proceeds to step S66, and if “middle speed”, the process proceeds to step S67. If so, the process proceeds to step S68.

In step S65, which proceeds to the “ultra-low speed” in which the highest communication quality can be expected, the communication quality is extremely good. Therefore, the probability that retransmission will occur is reduced, the generation of empty resources is reduced, and all retransmissions are performed. Dynamic allocation can perform efficient communication. In consideration of this, the retransmission number control unit 150b controls the number of retransmissions to 0 so that retransmission (fixed allocation) at a preset first frequency is stopped, and all retransmissions are second. Dynamic allocation to the frequency of In step S66, the process proceeds to “low speed” in which the second highest communication quality can be expected, the retransmission number control unit 150b controls the number of retransmissions for fixed allocation to 1, performs fixed allocation for one retransmission, and performs the second retransmission. Dynamically allocate the rest. In step S67, which proceeds in the case of “medium speed” where there is a possibility that the communication quality may be deteriorated, the retransmission number control unit 150b controls the fixed number of retransmissions to 2, and allocates two retransmissions fixedly, Dynamic allocation is performed after the third retransmission. In step S68, which proceeds in the case of “high speed” where there is a high possibility of becoming an environment in which communication quality has deteriorated, the retransmission number control unit 150b controls the number of retransmissions of fixed allocation to 3, and performs fixed allocation of 3 retransmissions, Dynamic allocation is performed after the fourth retransmission.

In the next step S69, the retransmission number control unit 150b determines whether or not the allocation method determined in step S65, step S66, step S67, or step S68 matches the current allocation method. In step S69, if the current allocation method matches the allocation method determined in the preceding step (step S65, step S66, step S67 or step S68), the process proceeds to step S70 and the current allocation method is changed. maintain. On the other hand, if the current allocation method and the allocation method determined in the preceding step do not match in step S69, the process proceeds to step S71, and the retransmission number control unit 150b sets the allocation method to steps S65 and S66. , Change to the allocation method determined in step S67 or step S68. In addition, after execution of step S70 or step S71, it returns to step S61 and repeats the said allocation system change procedure. For this reason, when a transmission packet is generated, the allocation method is changed at any time according to a change in communication quality.

In the wireless communication apparatus (base station) and the wireless communication method executed by the wireless communication apparatus (base station) according to the second embodiment, the allocation method determination procedure of FIG. 10 is performed. In other words, not only at the start of communication but also during communication, the number of retransmissions increases as the moving speed of the communication partner (terminal) increases according to the moving speed of the communication partner (terminal). The number of retransmissions of fixed allocation is controlled so that the number of retransmissions decreases as the movement speed decreases, and retransmission is performed using the preset first frequency for the number of retransmissions. On the other hand, for retransmissions that exceed the number of retransmissions, the number of retransmissions is controlled so that the number of retransmissions for dynamic allocation increases as the movement speed decreases, and is arbitrarily set with the communication partner (terminal) for the number of retransmissions. Control is performed to perform retransmission at the second frequency. As described above, in the second embodiment, the number of times that retransmission is fixedly allocated is increased according to the degree of communication quality as the communication quality deteriorates as the moving speed of the communication partner (terminal) increases. At the same time, in the second embodiment, the number of times of fixed allocation of retransmissions is reduced and the number of times of dynamic allocation of retransmissions is increased as the communication quality improves as the moving speed of the communication partner (terminal) decreases. As a result, it is possible to reduce both empty resources during retransmission and overhead due to dynamic allocation, and it is possible to optimize both empty resources during retransmission and overhead due to dynamic allocation to improve frequency utilization efficiency.

The outline of the allocation method determination procedure and the allocation method change procedure in the wireless communication apparatus (base station) of the second embodiment described above is as follows. That is, according to the movement speed of the communication partner (terminal), the number of retransmissions increases as the movement speed increases, and the number of retransmissions is fixed so that the number of retransmissions decreases as the movement speed decreases. Is dynamically allocated. However, for example, the allocation method determination procedure and the allocation method change procedure as in the first embodiment described above can be used in combination. That is, according to the communication quality level, the number of retransmissions is increased as the communication quality level is lower, and the number of retransmissions is fixed so that the number of retransmissions is decreased as the communication quality level is higher. The allocation scheme determination procedure to be allocated and the allocation scheme change procedure can be used in combination with the present embodiment.

According to the present invention, the number of retransmissions at the preset first frequency is controlled according to the communication quality of the wireless propagation path with the communication partner so that the number of retransmissions decreases as the communication quality increases, for example. To do. In addition, according to the present invention, for retransmission exceeding the number of retransmissions, control is performed so that retransmission is performed at a second frequency arbitrarily set with a communication partner. In the present invention, for example, the number of retransmissions to be fixedly allocated is increased according to the degree of communication quality as the communication quality is deteriorated, and the number of retransmissions to be dynamically allocated is increased by decreasing the number of retransmissions to be fixedly allocated as the communication quality is improved. Therefore, it is possible to reduce both empty resources at the time of retransmission and overhead due to dynamic allocation. Further, it is possible to improve both frequency resources efficiency by optimizing both empty resources at the time of retransmission and overhead due to dynamic allocation.

Further, according to the present invention, the number of retransmissions at a preset first frequency is controlled according to the moving speed of the communication partner, for example, so that the number of retransmissions decreases as the moving speed of the communication partner decreases. To do. Furthermore, according to the present invention, for retransmission exceeding the number of retransmissions, control is performed so that retransmission is performed at a second frequency arbitrarily set with a communication partner. In the present invention, for example, as the moving speed of the communication partner increases, the number of retransmissions to be fixedly allocated is increased according to the moving speed of the communication partner, and the number of retransmissions to be fixedly allocated increases as the moving speed of the communication partner decreases. Reduce the number of retransmissions to be dynamically allocated. Thereby, it is possible to reduce both empty resources at the time of retransmission and overhead due to dynamic allocation. Further, it is possible to improve both frequency resources efficiency by optimizing both empty resources at the time of retransmission and overhead due to dynamic allocation.

100,300 Wireless communication device (base station)
110 antenna 130 RF unit 140 RF control unit

140a reception unit

140b transmission unit 150 system control unit 150a communication quality acquisition unit 150b retransmission count control unit 150c retransmission control unit 160 input unit 170 display unit 180 system storage unit 180a communication quality information storage unit 200 Communication partner (terminal)
350a Moving speed acquisition unit 380a Moving speed information storage unit

Claims

When retransmitting data to a communication partner, a wireless communication device that performs the retransmission using a preset frequency,
A communication quality acquisition unit for acquiring communication quality of a radio propagation path between the communication partners;
In accordance with the communication quality acquired by the communication quality acquisition unit, a retransmission number control unit that controls the number of retransmissions at a preset first frequency;
For retransmission exceeding the number of retransmissions controlled by the retransmission number control unit, a retransmission control unit that controls to perform the retransmission at the second frequency set with the communication partner;
A wireless communication apparatus comprising:
The wireless communication apparatus according to claim 1, wherein the retransmission number control unit controls the number of retransmissions to decrease as the communication quality acquired by the communication quality acquisition unit increases.
The retransmission number control unit controls the number of retransmissions so that retransmission at the first frequency is stopped when the communication quality acquired by the communication quality acquisition unit exceeds a predetermined communication quality. The wireless communication apparatus according to claim 1 or 2.
When retransmitting data to a communication partner, a wireless communication method for performing the retransmission using a preset frequency,
A communication quality acquisition step of acquiring communication quality of a radio propagation path between the communication partners;
A retransmission count control step for controlling the number of retransmissions at a preset first frequency according to the communication quality acquired in the communication quality acquisition step;
For retransmission exceeding the number of retransmissions controlled in the retransmission number control step, a retransmission control step for controlling to perform the retransmission at a second frequency set with the communication partner;
A wireless communication method.
When retransmitting data to a communication partner, a wireless communication device that performs the retransmission using a preset frequency,
A moving speed acquisition unit that acquires the moving speed of the communication partner;
A retransmission number control unit that controls the number of retransmissions at a preset first frequency according to the moving speed of the communication partner acquired by the moving speed acquisition unit;
For retransmission exceeding the number of retransmissions controlled by the retransmission number control unit, a retransmission control unit that controls to perform the retransmission at the second frequency set with the communication partner;
A wireless communication apparatus comprising:
The wireless communication apparatus according to claim 5, wherein the retransmission number control unit controls the number of retransmissions to decrease as the movement speed of the communication partner acquired by the movement speed acquisition unit decreases.
The retransmission number control unit controls the number of retransmissions so that retransmission at the first frequency is stopped when the movement speed of the communication partner acquired by the movement speed acquisition unit is less than a predetermined speed. The wireless communication apparatus according to claim 5, wherein the wireless communication apparatus is a wireless communication apparatus.
8. The moving speed acquisition unit according to claim 5, wherein the moving speed of the communication partner is acquired by being notified of the moving speed of the communication partner measured by the communication partner. A wireless communication device according to 1.
When retransmitting data to a communication partner, a wireless communication method for performing the retransmission using a preset frequency,
A moving speed acquisition step of acquiring the moving speed of the communication partner;
A retransmission number control step for controlling the number of retransmissions at a preset first frequency according to the movement speed of the communication partner acquired in the movement speed acquisition step;
For retransmission exceeding the number of retransmissions controlled in the retransmission number control step, a retransmission control step for controlling to perform the retransmission at a second frequency set with the communication partner;
A wireless communication method.